Whether a simple planting of petunias and marigolds or a large border garden, few things in life are as satisfying to our spirits as our own flower garden. As with arranging a floral bouquet, designing a flower garden is like painting a picture with plant material.

Some believe the best part of gardening is in the planning, others believe it’s in the planting, and still others believe it’s enjoying the garden once it is mature. Whatever your source of enjoyment, a few simple tips on choosing plants for the garden will guide you to satisfaction in the end.

For many people, starting a garden from nothing but a bit of open space in the landscape is at first a daunting task. Choosing the right site — which for most flowers means one which receives sunlight throughout the day — making sure the soil is well drained, loamy, and high in organic matter are all things to first consider. Once the location has been determined, the quest for plants to adorn the garden begins.

All flower gardens, whether a free-standing bed in the middle of the lawn or a border garden flanked with a hedge or fence, can be broken up into three visual sections: the fore-, mid- and background.

For gardens against an architectural backdrop, the front of the garden provides the foreground, the middle the midground, and furthest part the background. For gardens located in the middle of a lawn, the center of the bed is the background and the portions nearest the grass the foreground. Everything in between is the midground.

The size of each plant determines where in the garden it should be placed. Low-growing or compact plants 3 to 12 inches in height belong in the foreground. Petunias, impatiens, portulaca, creeping phlox, thyme and marigolds may all be considered forground specimens.

Plants 12 to 24 inches in height, such as lady’s mantle, snapdragons, lavatera, poppy and iris, are considered midground plants. Garden phlox, delphinium, hollyhock, cleome, love-lies-bleeding and all other plants that grow to be taller than 24 inches belong in the background of the flower bed.

Visualizing the garden in these three general areas can help make selecting plants an easier task.

Say you’re designing a border garden that is 12 feet long and six feet wide. To the back of the garden is a split-rail fence, with turf surrounding the other three sides.

Visualize the three sections of the bed: starting from the front of the bed, the first two feet of space will be designated as the foreground, the middle two feet as the midground and the back two feet, the back ground.

Therefore, out of 72 square feet of bed space, each section of the garden will have about 24 square feet devoted to plants that suit the requirements of design.

Considering the colors you want to use to “paint” your garden and the functions you want to incorporate — for example you might want to grow some plants which you can use for cut flowers or medicinal herbs — choose plants that will satisfy your needs.

As you select the plants separate them — mentally or on paper — according to their placement in the garden. Keep in mind that in general you need fewer background plants than midground plants and fewer midground plants than foreground plants, simply because background plants take up more space than mid- and foreground specimens.

When installing the plants, be sure to exercise some flexibility. Place some midground plants in the background, some foreground plants in the midground and so on. This will yield a more natural effect in the garden, blending the sections so they aren’t rigid and obvious.

With time and experience we all learn that some plants don’t always grow exactly as the catalog and seed packet describes. Light conditions, wind, fertility and soil all have dramatic effects on how a plant performs. Some plants which have the genetic propensity to grow 3 or 4 feet in height sometimes never get above 2 feet in our climate. Thus, for a few plants — perennials, in specific — determining where they belong in the garden can be a task that spans a few years.

In general, though, most plants are true to form, growing — and thriving — in the space we call their home.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o Maine Weekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone number.